How to draw Lewis structure of molecules with N

Many times, I find it hard to draw correct Lewis structure of molecules with nitrogen. For instance: the Lewis structure of H2CNN. I thought it should be double bond between C and N and single bond between N and N, like this:
But actually it's not. I have done many problems like this wrong.

That's certainly a correct Lewis structure for this molecule. However, when viewed at as a representation of a valence bond structure, it may not be a structure with high importance.
The point is that the rightmost nitrogen has only a sextet. Transforming the lone pair of the central atom into a bond between the two nitrogens will lead to a structure fulfilling the octet rule on all atoms.

Could you give some more examples (just the molecular formula, not necessarily your attempts) of problems like this (since as you say you've tried several of them)? Because I originally did not get this one straight away and would love to work on a few more :)